SWODY1
SPC AC 190434
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1134 PM CDT FRI APR 18 2008
VALID 191200Z - 201200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
UPPER AIR PATTERN TRANSITION IS UNDERWAY...AS LARGE CYCLONE NOW
CENTERED OVER SRN BC BECOMES MORE FIRMLY ESTABLISHED OVER PACIFIC
NW. SEVERAL MESOSCALE VORTICITY CENTERS/LOBES ARE EXPECTED TO
ROTATE AROUND BROADER SCALE CYCLONE CENTER OVER THAT REGION...WITH
STG HEIGHT FALLS LIKELY ACROSS MUCH OF CENTRAL/NRN GREAT BASIN
REGION. AS THAT OCCURS...DOWNSTREAM CENTRAL CONUS RIDGE WILL SHIFT
EWD...ALONG WITH SMALLER BUT STILL WELL DEFINED MID/UPPER LOW NOW
OVER MO. LATTER CYCLONE IS EXPECTED TO MOVE ESEWD TO CENTRAL
APPALACHIANS BY END OF PERIOD...AS IT BEGINS TO UNDERCUT ERN CONUS
RIDGE AND TREND TOWARD REX PATTERN OVER ADJACENT ATLANTIC WATERS.
WITH EACH RUN TIME...MORE DETERMINISTIC AND ENSEMBLE GUIDANCE
PACKAGES ARE TRENDING TOWARD THIS SCENARIO AS OPPOSED TO NEWD
EJECTION AROUND RIDGING.
ASSOCIATED SFC CYCLONE -- NOW EVIDENT OVER UPPER MS VALLEY -- IS
EXPECTED TO OCCLUDE AND FILL SOMEWHAT...MOVING ENEWD TOWARD LOWER
MI. ACCOMPANYING COLD FRONT WILL MOVE EWD ACROSS E GULF COASTAL
PLAIN AND MUCH OF GA BY 20/00Z. BOUNDARY WILL BE GRADUALLY
FRONTOLYTIC...LOSING MUCH OF ITS THERMAL DEFINITION BUT STILL
APPARENT IN MOISTURE AND THETAE GRADIENTS...AND AS SUCH...ACTING
MUCH LIKE EFFECTIVE DRYLINE.
...CENTRAL APPALACHIANS REGION...
ONE OR MORE BANDS OF TSTMS MAY DEVELOP DURING AFTERNOON FROM SRN OH
SEWD ACROSS ERN KY AND WV...AND OVER PORTIONS WRN VA INTO CENTRAL
CAROLINAS. COLDEST AIR ALOFT IS EXPECTED OVER HIGHLANDS OF
WV/KY...WITH STRONGEST SFC HEATING AND SUBCLOUD MIXING PROBABLE
FARTHER S ACROSS CAROLINAS. DEEP-LAYER SHEAR WILL STRENGTHEN WITH
NWWD EXTENT FROM CAROLINAS TOWARD ERN KY...ALTHOUGH LOW LEVEL LAPSE
RATES AND OVERALL BUOYANCY WILL BE MRGL. SOME GUSTS APCHG SVR
LIMITS...AND CAPABLE OF MINOR DAMAGE...MAY OCCUR FROM THIS
ACTIVITY...AND HAIL NEAR SVR LEVELS MAY OCCUR AS WELL. LACK OF MORE
ROBUST INSTABILITY PRECLUDES CATEGORICAL OUTLOOK ATTM. ACTIVITY
SHOULD DIMINISH CONSIDERABLY AFTER 00Z WITH LOSS OF CONTRIBUTION TO
LOW LEVEL BUOYANCY FROM DIABATIC SFC HEATING.
...COASTAL NWRN CONUS...
19/00Z 500 MB ANALYSES SHOWED TEMPS NEAR -40 DEG C...WHICH
CONTRIBUTED TO SFC BASED BUOYANCY IN NRN VANCOUVER ISLAND RAOB YZT
-- DESPITE SFC TEMPS MID 40S F. AS ASSOCIATED AIR MASS ALOFT
SETTLES SWD ACROSS PACIFIC NW...POTENTIAL FOR ISOLATED TO WIDELY
SCATTERED TSTMS WILL INCREASE AMIDST POCKETS OF INLAND DIABATIC
HEATING...AND MORE FAVORABLE BOUNDARY LAYER MOISTURE W OF CASCADES.
WITH EXTREMELY COLD AIR ALOFT...LOW FREEZING LEVELS AND STEEP LAPSE
RATES ATOP PACIFIC MOIST LAYER...EXPECT RELATIVELY SHALLOW DEPTH
BETWEEN ICING LAYERS AND GROUND...ALONG WITH MLCAPES UP TO ABOUT 200
J/KG. THOUGH MOST SHOULD REMAIN BELOW SVR LEVELS...ISOLATED
MRGL-SVR HAIL CANNOT BE RULED OUT.
..EDWARDS/GRAMS.. 04/19/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment